DBCombo Problem

[sajith]

Hi, can some help me

i have two DBcombo in my dialog,I Populate the second DBcombo on the ON CHANGE event of the first one.
But the problem is when the on CHANGE event of the first DBcombo fires the second DBcombo is populated But the first element is displayed as blank.

Regards,
sajith

[James Bott]

Sayith,

DBcombo puts in a blank item to show that no item has been selected. Users may not always make a selection, and without a blank item, the first item would appear to have been selected when it hasn't been.

It is not a good idea to default a field to a value, because the user may not know what that data should be. It is better to leave it blank than to force them to select something which is wrong.

James

[Marcelo Via Giglio]

Hello,

this is a dbcombo modification, I added some features

- display no blank selecction (first item from the list)
- condition for the items in the list
- use index tag order to fill the list from the db table
- the prompt and result list can be an expression, this means you can combine field in the result and the showed list
like "alltrim(lastname) + ' - ' + alltrim(firstname) "

I think this is all

regards

Marcelo

Code: Select all  Expand view  RUN

*********************************************************************
* File Name:    DBCombo.ch
* Author:   Elliott Whitticar
* Created:  04/23/96
* Description:  Preprocessor directives for TDBCombo class.
*********************************************************************
#ifndef _DBCOMBO_CH
#define _DBCOMBO_CH

/*----------------------------------------------------------------------------//
!short: DBCOMBO */

#xcommand REDEFINE DBCOMBO [ <oCbx> VAR ] <cVar> ;
             [ <items: ITEMS, PROMPTS> <aItems> ] ;
             [ ID <nId> ] ;
             [ <dlg:OF,WINDOW,DIALOG> <oWnd> ] ;
             [ <help:HELPID, HELP ID> <nHelpId> ] ;
             [ ON CHANGE <uChange> ] ;
             [ VALID   <uValid> ] ;
             [ <color: COLOR,COLORS> <nClrText> [,<nClrBack>] ] ;
             [ <update: UPDATE> ] ;
             [ MESSAGE <cMsg> ] ;
             [ WHEN <uWhen> ] ;
             [ BITMAPS <acBitmaps> ] ;
             [ ON DRAWITEM <uBmpSelect> ] ;
         [ ALIAS <cAlias> ] ;
         [ ITEMFIELD <cFldItem> ] ;
         [ LISTFIELD <cFldList> ] ;
             [ <list: LIST, PROMPTS> <aList> ] ;
         [ <noblank: NOBLANK>] ;
             [ ORDER <orden> ] ;
         [ FOR <uCond> ] ;
       => ;
          [ <oCbx> := ] TDBCombo():ReDefine( <nId>, bSETGET(<cVar>),;
             <aItems>, <oWnd>, <nHelpId>, <{uValid}>, [{|Self|<uChange>}],;
             <nClrText>, <nClrBack>, <cMsg>, <.update.>, <{uWhen}>,;
             <acBitmaps>, [{|nItem|<uBmpSelect>}], ;
             <cAlias>, <cFldItem>, <cFldList>, <aList>, <.noblank.>, <{uCond}>, <orden> )

#endif
 

Code: Select all  Expand view  RUN

/*
File Name:   DBCombo.prg
Author:      Elliott Whitticar, 71221.1413@Compuserve.com
Created:     4/25/96
Description: Database-aware ComboBox class. Can show one field and return another.
Revision:    Changes made by James Bott, Intellitech. jbott@compuserve.com
             11/2/2003 Changed manifest constants to also be 32bit compatible.
                       Initiate(): Changed to call TControl:initiate()
                       New() & Redefine() : Changed to return self (were incorrectly returning nil).
                       Refill() - Now adds blank record to all lists. (Was incorrectly showing first
                       item when variable was empty.)
             5/21/2004 Added keyChar method with incremental search. Space key resets search.
                       Of course, data has to be in sort order.
             6/14/2005 Changed to default cAlias to alias().
                       Refill() Changed name to Fill(). Added new method Refill().
                       Had to do this to properly reinitialize the control when refilled.
             6/15/2005 Updated the Default() method to fix some bugs (dropdown not working
                       after Refill(). Changed dbcombo.ch to allow specifying fields with
                       or without guotes. E.G. ITEMFIELD city or ITEMFIELD "city"
             7/21/2005 Fixed bug. When using autocomplete was returning numeric instead of char.
             2/23/2006 Fixed several bugs when passing arrays from the new or redefine methods.
             2/24/2006 LostFocus() Modified so aItems can be numeric.
             3/31/2006 KeyChar() Fixed bug when both bChanged and lUpdate were used.
             04/3/2006 Refill() Fixed typo.
             7/02/2006 Update() Added new method. Slightly different than Refill(). - Antonio Linares

//----------------------------------------------------------------------------//
Notes

The TDBCombo class provides a combo-box which displays one field from
a table (such as DeptName) and returns another (such as DeptID). Table can
be indexed and/or filtered, just set them before calling DBCombo.

To use dbcombo as a resource, define the resource as a combobox. Make sure the ComboBox
is not configured to sort aList, or DBCombo will not return the matching element of aItems.
Then REDEFINE the combobox control as a DBCOMBO.

aList must be character. aItems can be character or numeric.


*/
//----------------------------------------------------------------------------//



#include "FiveWin.ch"
#include "Constant.ch"

#ifndef __CLIPPER__
   #define COMBO_BASE      320
#else
   #define COMBO_BASE  WM_USER
#endif
#define CB_ADDSTRING     ( COMBO_BASE + 3 )
#define CB_DELETESTRING  ( COMBO_BASE +  4 )
#define CB_GETCURSEL     ( COMBO_BASE +  7 )
#define CB_INSERTSTRING  ( COMBO_BASE + 10 )
#define CB_RESETCONTENT  ( COMBO_BASE + 11 )
#define CB_FINDSTRING    ( COMBO_BASE + 12 )
#define CB_SETCURSEL     ( COMBO_BASE + 14 )
#define CB_SHOWDROPDOWN  ( COMBO_BASE + 15 )
#define CB_ERR              -1

#define COLOR_WINDOW       5
#define COLOR_WINDOWTEXT   8

#define MB_ICONEXCLAMATION  48   // 0x0030

#define GWL_STYLE          -16

#ifdef __XPP__
#define Super ::TComboBox
#endif

//------------------------------------------------------------------------------

#include "FiveWin.ch"
//----------------------------------------------------------------------------//

CLASS TDBCombo FROM TComboBox

   DATA  cAlias      // Workarea alias for fields to display.
   DATA  cFldList    // Field to display in the ComboBox.
   DATA  cFldItem    // Field to return in the bound variable.
   DATA  aList       // Array of display items corresponding to aItems.
                     // May be specified in the constructor or read from
                     // cAlias->cFldList
   DATA cSearchKey   // Holds current search key for incremental search.
   DATA lSound init .T. // Use sound

   DATA lnoBlank       // si deseamos que no haya uno en blanco => .T.
   DATA bFor           // MVG
   DATA bOrder         // MVG

   METHOD New( nRow, nCol, bSetGet, aItems, nWidth, nHeight, oWnd, nHelpId, ;
              bChange, bValid, nClrText, nClrBack, lPixel, oFont, ;
              cMsg, lUpdate, bWhen, lDesign, acBitmaps, bDrawItem, ;
              cAlias, cFldItem, cFldList, aList ) CONSTRUCTOR

   METHOD ReDefine( nId, bSetGet, aItems, oWnd, nHelpId, bValid, ;
              bChange, nClrText, nClrBack, cMsg, lUpdate, ;
              bWhen, acBitmaps, bDrawItem, ;
              cAlias, cFldItem, cFldList, aList ) CONSTRUCTOR

   METHOD Add( cItem, nAt, cList )

   METHOD Default()

   METHOD Del( nAt )

   METHOD DrawItem( nIdCtl, nPStruct )

   METHOD Fill()  // Fill aItems, aList from database. Used internally only.

   METHOD Initiate( hDlg )

   METHOD Insert( cItem, nAt, cList )

   METHOD KeyChar( nKey, nFlags )     // Incremental search

   METHOD ListGet()                   // Returns the selected element of ::aList

   METHOD LostFocus()

   METHOD Modify( cItem, nAt, cList )

   METHOD Refill()                    // Refill aItems and aList from cFldItem and cFldList

   METHOD SetItems( aItems, aList )

   METHOD Update()

ENDCLASS

//----------------------------------------------------------------------------//

METHOD New( nRow, nCol, bSetGet, aItems, nWidth, nHeight, oWnd, nHelpId, ;
            bChange, bValid, nClrFore, nClrBack, lPixel, oFont, ;
            cMsg, lUpdate, bWhen, lDesign, acBitmaps, bDrawItem, ;
            cAlias, cFldItem, cFldList, aList, lnoBlank, bFor, border ) CLASS TDBCombo

   DEFAULT cAlias := alias(),;
           cFldList := ""   ,;
           cFldItem := ""   ,;
           aList    := {}   ,;
           aItems   := {}   ,;
           lnoBlank := .F.  ,;    // MVG
           bFor     := {|| .T. }  // MVG

   ::lnoBlank := lnoBlank         // MVG
   ::bFor     := bFor             // MVG
   ::border   := border           // MVG

   ::aList    := aList
   ::aItems   := aItems
   ::cAlias   := cAlias
   ::cFldList := cFldList
   ::cFldItem := cFldItem
   ::cSearchKey:=""
   if empty(::aItems) .and. empty(::aList)
      ::Fill()
   else
      ::cAlias:=""
   endif

   Super:New( nRow, nCol, bSetGet, ::aItems, nWidth, nHeight, oWnd, nHelpId, ;
      bChange, bValid, nClrFore, nClrBack, lPixel, oFont, ;
      cMsg, lUpdate, bWhen, lDesign, acBitmaps, bDrawItem )

return self

//----------------------------------------------------------------------------//

METHOD ReDefine( nId, bSetGet, aItems, oWnd, nHelpId, bValid, ;
                 bChange, nClrFore, nClrBack, cMsg, lUpdate, ;
                 bWhen, acBitmaps, bDrawItem, ;
                 cAlias, cFldItem, cFldList, aList, lnoBlank, bFor, border ) CLASS TDBCombo

   DEFAULT cAlias := alias(),;
         cFldList := ""     ,;
         cFldItem := ""     ,;
         aList    := {}     ,;
         aItems   := {}     ,;
         lnoBlank := .F.    ,;  // MVG
         bFor     := {|| .T. }  // MVG

   ::lnoBlank := lnoBlank       // MVG
   ::bFor     := bFor           // MVG
   ::border   := border         // MVG

   ::aList    := aList
   ::aItems   := aItems
   ::cAlias   := cAlias
   ::cFldList := cFldList
   ::cFldItem := cFldItem
   ::cSearchKey:=""
   if empty(::aItems) .and. empty(::aList)
      ::Fill()
   else
      ::cAlias:=""
   endif

   Super:ReDefine( nId, bSetGet, ::aItems, oWnd, nHelpId, bValid, ;
               bChange, nClrFore, nClrBack, cMsg, lUpdate, ;
               bWhen, acBitmaps, bDrawItem )

return self

//----------------------------------------------------------------------------//

METHOD Add( cItem, nAt, cList ) CLASS TDBCombo
   // Note that compared to the parent class, we've added an arg at the end.

   DEFAULT nAt := 0
   DEFAULT cList := cItem

   if nAt == 0
     AAdd( ::aItems, cItem )
     AAdd( ::aList,  cList )
   else
     ASize( ::aItems, Len( ::aItems ) + 1 )
     ASize( ::aList, Len( ::aList ) + 1 )
     AIns( ::aItems, nAt )
     AIns( ::aList, nAt )
     ::aItems[ nAt ] = cItem
     ::aList[ nAt ] = cList
   endif

   ::SendMsg( CB_ADDSTRING, nAt, cList )

return nil

//----------------------------------------------------------------------------//

METHOD Default() CLASS TDBCombo

   local cStart := Eval( ::bSetGet )
   if ! Empty( ::hWnd ) .and. ::nStyle == CBS_DROPDOWNLIST
      ::nStyle := GetWindowLong( ::hWnd, GWL_STYLE )
   endif

   if cStart == nil
      Eval( ::bSetGet, If( Len( ::aItems ) > 0, ::aItems[ 1 ], "" ) )
      cStart = If( Len( ::aItems ) > 0, ::aItems[ 1 ], "" )
   endif

   AEval( ::aList, { | cList, nAt | ::SendMsg( CB_ADDSTRING, nAt, cList ) } )

   if ValType( cStart ) != "N"
      ::nAt = AScan( ::aList, { | cList | Upper( AllTrim( cList ) ) == ;
                                           Upper( AllTrim( cStart ) ) } )
   else
      ::nAt = cStart
   endif

   ::nAt = If( ::nAt > 0, ::nAt, 1 )

   if cStart == nil
      ::Select( ::nAt )
   else
      ::Set( cStart )
   endif

   IF ::lnoBlank          // MVG
      ::Select( ::nAt )   // MVG
   ENDIF                  // MVG

return nil

//----------------------------------------------------------------------------//

METHOD Del( nAt ) CLASS TDBCombo

   DEFAULT nAt := 0

   if nAt != 0
      ADel( ::aItems, nAt )
      ADel( ::aList, nAt )
      ASize( ::aItems, Len( ::aItems ) - 1 )
      ASize( ::aList, Len( ::aList ) - 1 )
      ::SendMsg( CB_DELETESTRING, nAt - 1 )
   endif

return nil

//----------------------------------------------------------------------------//

METHOD DrawItem( nIdCtl, nPStruct ) CLASS TDBCombo

return LbxDrawItem( nPStruct, ::aBitmaps, ::aList, ::nBmpWidth, ::bDrawItem )

//----------------------------------------------------------------------------//

METHOD Initiate( hDlg ) CLASS TDbCombo

   ::TControl():Initiate( hDlg )
   ::Default()
   ::change() // MVG

RETURN NIL

//----------------------------------------------------------------------------//

METHOD Insert( cItem, nAt, cList ) CLASS TDBCombo

   DEFAULT nAt := 0
   DEFAULT cList := cItem

   if nAt != 0
      ASize( ::aItems, Len( ::aItems ) + 1 )
      ASize( ::aList, Len( ::aList ) + 1 )
      AIns( ::aItems, nAt )
      AIns( ::aList, nAt )
      ::aItems[ nAt ] = cItem
      ::aList[ nAt ] = cList
      ::SendMsg( CB_INSERTSTRING, nAt - 1, cList )
   endif

return nil

//----------------------------------------------------------------------------//

METHOD KeyChar( nKey, nFlags) CLASS TDBCombo

   local nNewAT := 0, nOldAT:=::nAT

   // Incremental search
   if nKey = 32   // space resets the search
      ::cSearchKey := ""
      ::Set( If( ValType( Eval( ::bSetGet ) ) == "N", 1, ::aItems[ 1 ] ) )
   else
      if nKey = VK_BACK
         ::cSearchKey := left(::cSearchKey,Len(::cSearchKey)-1)
      else
         ::cSearchKey += upper(chr(nKey))
      endif

      nNewAT := ascan(::aList, {|x| LEFT( upper(x), LEN(::cSearchKey) ) = ::cSearchKey} )

      if nNewAt != nOldAt .and. nNewAT != 0  // If found and changed

         if ::lSound
            tone(60,.3) // sound if searchkey found
         endif

         ::Set( If( ValType( Eval( ::bSetGet ) ) == "N", nNewAt, ::aItems[ nNewAt ] ) )

         if ::bChange != nil

            if ::oGet != nil                        // Always not nil for dropdown
               ::oGet:VarPut( Eval( ::bSetGet ) )   // udate variable before calling bChange
               ::oGet:Refresh()
            endif

            Eval( ::bChange, Self, ::varGet() )

         endif

         return 0

      else
         ::cSearchKey := left(::cSearchKey,Len(::cSearchKey)-1)
      endif
   endif

   Super:KeyChar(nKey, nFlags)

RETURN 0   // Must be 0 - We don't want API default behavior.


//----------------------------------------------------------------------------//

METHOD ListGet() CLASS TDBCombo

   local cRet, nAt := ::SendMsg( CB_GETCURSEL )

   if nAt != CB_ERR
      ::nAt = nAt + 1
      cRet :=  ::aList[ ::nAt ]
   else
      cRet := GetWindowText( ::hWnd )
   endif

return cRet

//----------------------------------------------------------------------------//

METHOD LostFocus() CLASS TDBCombo

   local nAt := ::SendMsg( CB_GETCURSEL )

   if nAt != CB_ERR
      ::nAt = nAt + 1
      Eval( ::bSetGet, ::aItems[ ::nAt ] )
   else
      Eval( ::bSetGet, GetWindowText( ::hWnd ) )
   endif

   ::cSearchKey:=""

return nil

//----------------------------------------------------------------------------//

METHOD Modify( cItem, nAt, cList ) CLASS TDBCombo

   DEFAULT nAt := 0
   DEFAULT cList := cItem

   if nAt != 0
      ::aItems[ nAt ] = cItem
      ::aList[ nAt ] = cList
      ::SendMsg( CB_DELETESTRING, nAt - 1 )
      ::SendMsg( CB_INSERTSTRING, nAt - 1, cList )
   endif

return nil

//----------------------------------------------------------------------------//

METHOD Fill() CLASS TDBCombo

   // Refill aItems and aList from cAlias->cFldItem and cAlias->cFldList

   LOCAL nOldRecNo
   LOCAL nItem, nList
   LOCAL antord, antarea  //MVG

   IF ::cAlias == ""
      // There's no workarea defined, so do nothing.
      RETURN NIL
   END IF

   IF ( antarea := SELECT( ::cAlias ) ) == 0
      MsgAlert( "TDBCombo:Fill() - Alias '" + ::cAlias + "' does not exist." )
      RETURN NIL
   ELSE                        // MVG
      DBSelectArea( ::cAlias ) //MVG
   END IF

   ::aItems := { }
   ::aList := { }

   IF ::border != NIL                                         // MVG
      antord := ( ::cAlias ) -> ( ordSetfocus( ::border ) )   // MVG
   ENDIF

   //IF (nItem := (::cAlias)->(FIELDPOS( ::cFldItem ))) > 0
   //   IF (nList := (::cAlias)->(FIELDPOS( ::cFldList ))) > 0

         nOldRecNo := (::cAlias)->(RECNO())

         // Make first record blank if we want (so you can have an empty field)
         IF ! ::lnoBlank  // MVG
            (::cAlias)->(DBGOBOTTOM())
            (::cAlias)->(DBSKIP())
            //AADD( ::aItems, (::cAlias)->(FIELDGET( nItem )) )
            //AADD( ::aList, (::cAlias)->(FIELDGET( nList )) )
            AADD( ::aItems, "" ) // MVG
            AADD( ::aList, "" )  // MVG
         ENDIF            // MVG

         (::cAlias)->(DBGOTOP())

         DO WHILE ! (::cAlias)->(EOF())
            IF Eval( ::bFor ) // MVG
               AAdd( ::aItems, &(::cFldItem) )
               AAdd( ::aList, &(::cFldList) )
               //AADD( ::aItems, (::cAlias)->(FIELDGET( nItem )) )
               //AADD( ::aList, (::cAlias)->(FIELDGET( nList )) )
            ENDIF
            (::cAlias)->(DBSKIP())
         ENDDO

         (::cAlias)->(DBGOTO( nOldRecNo ))

      //ELSE
      //   msgAlert("TDBCombo:Fill() - Fieldname "+::cFldList+" not found.")
      //ENDIF
   //ENDIF

   IF ::border != NIL                            // MVG
      ( ::cAlias ) -> ( ordSetfocus( antord ) )  // MVG
   ENDIF                                         // MVG

   DBSelectArea( antarea )

RETURN NIL

//----------------------------------------------------------------------------//

METHOD Refill() CLASS TDBCombo
   ::Reset()
   ::Fill()
   ::Default()
   ::Change()
return nil

//----------------------------------------------------------------------------//

METHOD SetItems( aItems, aList ) CLASS TDbCombo

   IF LEN(aItems) != LEN(aList)
      MsgAlert( "TDBCombo:SetItems(): aItems and aList must be same length." )
   ELSE
      ::cAlias:= ""
      ::Reset()
      ::aItems := aItems
      ::aList := aList
      ::Default()
      ::Change()
   END IF

RETURN NIL

//----------------------------------------------------------------------------//

METHOD Update() CLASS TDBCombo

   local bChange:= ::bChange

   ::bChange:= Nil
   ::Reset()
   ::Fill()
   ::Default()
   ::bChange := bChange

return nil

//----------------------------------------------------------------------------//
 

[sajith]

Dear James & MVG
Many thanks for ur Support.
MVG i tried ur code but Pblm still Remain.

Regards,
sajith

[Marcelo Via Giglio]

Hola,

redefine the second DBCOMBO with NOBLANK option

REDEFINE DBCOMBO ALIAS ....... NOBLANK

regards

Marcelo